値型java.lang.StringのデータベースをJSONObjectに変換できません

Question

以下のコードを使用して指定されたデータはデータベースに挿入されますが、ダイアログボックスに成功したかどうかは表示されません。

ターゲットAPIは23です。

gsonを使用する必要がありますか？

助けてください。

public class BackgroundTask extends AsyncTask<String, Void, String> { 

String register_url = "http://192.168.1.101/loginapp/register.php"; 

    Context ctx; 

    Activity activity; 

    ProgressDialog progressDialog; 

    AlertDialog.Builder builder; 

    public BackgroundTask(Context ctx) 
    { 
     this.ctx = ctx; 
     activity = (Activity)ctx; 
    } 

    @Override 
    protected void onPreExecute() { 
     builder = new AlertDialog.Builder(activity); 
     progressDialog = new ProgressDialog(ctx); 
     progressDialog.setTitle("Please wait..."); 
     progressDialog.setMessage("Connecting to server..."); 
     progressDialog.setIndeterminate(true); 
     progressDialog.setCancelable(false); 
     progressDialog.show(); 

     super.onPreExecute(); 
    } 

    @Override 
    protected String doInBackground(String... params) { 
     String method = params[0]; 
     if(method.equals("register")) 
     { 
      try { 
       URL url = new URL(register_url); 
       HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection(); 
       httpURLConnection.setRequestMethod("POST"); 
       httpURLConnection.setDoOutput(true); 
       httpURLConnection.setDoInput(true); 
       OutputStream outputStream = httpURLConnection.getOutputStream(); 
       BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8")); 
       String name = params[1]; 
       String email = params[2]; 
       String password = params[3]; 
       String data = URLEncoder.encode("name", "UTF-8")+"="+URLEncoder.encode(name,"UTF-8")+"&"+ 
         URLEncoder.encode("email","UTF-8")+"="+URLEncoder.encode(email,"UTF-8")+"&"+ 
         URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8"); 
       bufferedWriter.write(data); 
       bufferedWriter.flush(); 
       bufferedWriter.close(); 
       outputStream.close(); 
       InputStream inputStream = httpURLConnection.getInputStream(); 
       BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 
       StringBuilder stringBuilder = new StringBuilder(); 
       String line = ""; 
       while((line=bufferedReader.readLine()) != null) 
       { 
        stringBuilder.append(line+"\n"); 
       } 
       httpURLConnection.disconnect(); 
       Thread.sleep(5000); 
       // return string builder as normal string. 
       return stringBuilder.toString(); 

      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
     return null; 
    } 

    @Override 
    protected void onProgressUpdate(Void... values) { 
     super.onProgressUpdate(values); 
    } 

    @Override 
    protected void onPostExecute(String json) { 
     try { 
      progressDialog.dismiss(); 
      JSONObject jsonObject = new JSONObject(json); 
      //need to get json array from json object. 
      JSONArray jsonArray = jsonObject.getJSONArray("server_response"); 
      //now we can get each of the json data from json array. 
      JSONObject jo = jsonArray.getJSONObject(0); 
      //now we can read each data from json object; 
      String code = jo.getString("code"); 
      String message = jo.getString("message"); 
      if(code.equals("reg_true")) 
      { 
       showDialog("Registration Success..",message,code); 
      } 
      else if(code.equals("reg_false")) 
      { 
       showDialog("Registration failed..",message,code); 
      } 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 


    } 

    public void showDialog(String title, String message, String code) 
    { 
      builder.setTitle(title); 
      if(code.equals("reg_true")||code.equals("reg_false")) 
      { 
       builder.setMessage(message); 
       builder.setPositiveButton("OK", new DialogInterface.OnClickListener() { 
        @Override 
        public void onClick(DialogInterface dialog, int which) { 
         dialog.dismiss(); 
         activity.finish(); 
        } 
       }); 
       AlertDialog alertDialog = builder.create(); 
       alertDialog.show(); 

      } 
    } 
} 

Answer 1

doInBackground（）メソッドの戻り値は、onPostExecute（）に渡されます。このメソッド内 ：

@Override 
    protected String doInBackground(String... params) { 
     String method = params[0]; 
     if(method.equals("register")) 
     { 
      try { 
       URL url = new URL(register_url); 
       HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection(); 
       //.... 
       // return string builder as normal string. 
       return stringBuilder.toString(); 

      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
     return null;   //YOU ARE RETURNING NULL. CHECK WHETHER params[0] is "register" 
    } 
    //.... 
    @Override 
    protected void onPostExecute(String json) { //json might be null. Try to print it using log.debug() 
     try { 
      progressDialog.dismiss(); 
      JSONObject jsonObject = new JSONObject(json); //This might throw exception 
      //... 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 

ペーストビン内のログを貼り付けて、ここにリンクを添付してください。 また、参照してください：String cannot be converted to JSONObject exception